Mechanika最新文献

{"title":"Investigation of Drillability of CFRP/Al 7075 Stack","authors":"Yunus Emre Karakoca, A. Aytaç","doi":"10.5755/j02.mech.31038","DOIUrl":"https://doi.org/10.5755/j02.mech.31038","url":null,"abstract":"Composite/metal stack materials, which have excellent mechanical properties, are wideyl used in aerospace industry. However, their machining operation is challenging due to two different material. In this study stack materials consisting of CFRP and Al 7075-T6 were drilled with different drilling parematers to investigate delamination defect, thrust force, inner surface roughness of hole and wear of the cutting tool. Cutting speeds of 50 and 200 m/min, feed rates of 0.10 and 0.20 mm/rev were selected as cutting parameters. The materials were drilled respectively in CFRP/Al 7075 and Al 7075/CFRP directions to observe effect of machining direction in the experiments Drilling experiments were carried out with an uncoated 9 mm diameter drill at variable and constant speeds. Experimental results showed that the surface roughness increased with the increase of cutting speed and feed rate, delamination increased in experiments where cutting tool came out of CFRP, thrust force at variable speeds increased and low amount of wear of cutting tool thanks to internal cooling.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45420067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Theoretical Value for the Tip Radius of Cracks and Notches","authors":"Goksel Saracoglu","doi":"10.5755/j02.mech.31338","DOIUrl":"https://doi.org/10.5755/j02.mech.31338","url":null,"abstract":"In this paper, using Creager and Paris's blunt elliptical hole stress distribution area equation, it is applied to crack and circular hole shaped defects using the theoretical radius value, which equalizes the maximum stress at the defect tip in terms of value to fracture toughness. By providing value equality, critical fracture stresses of all defect dimensions and tensile strength of the material were determined with a single mechanical test data. Compared with the predictions of other methodologies, it was determined that the obtained data gave results closer to the experimental values.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47408278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Dynamics of a Pipe Robot with Nonlinear Interactions of Its Elements","authors":"K. Ragulskis, B. Spruogis, M. Bogdevičius, A. Matuliauskas, V. Mištinas, L. Ragulskis","doi":"10.5755/j02.mech.30467","DOIUrl":"https://doi.org/10.5755/j02.mech.30467","url":null,"abstract":"Systems in which vibrational displacements are limited because elastic forces increase practically up to unlimited values, are investigated. Here systems having one degree of freedom are investigated in which vibrations have specific qualities for the case of conservative systems as well as for the case of forced harmonic excitations. Typical expressions for nonlinear stiffness are proposed. Model of a pipe robot with limited values of displacements is presented and investigated. The model has two degrees of freedom: the displacement of the vibrating mass inside the pipe robot and the displacement of the pipe robot itself. Motion of the pipe robot in the negative direction as well as motion of the pipe robot in the positive direction for different parameters of the system is observed. For high amplitude of excitation, the distance travelled by the pipe robot is much greater than for low amplitude of excitation. The obtained results are used in the process of design of pipe robots.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47794657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hybrid Experimental-Numerical Investigation on Plastic Deformation and Ductile Failure of Anisotropic Sheet Metals","authors":"Lin Wang","doi":"10.5755/j02.mech.27705","DOIUrl":"https://doi.org/10.5755/j02.mech.27705","url":null,"abstract":"The plastic deformation and ductile failure behaviors of anisotropic AISI 1018 low carbon steel and C260 Cu-Zn brass under uniaxial tensile loading were investigated. The full-filed surface deformation of U-notched sheet metal was measured by digital image correlation technique. Three-dimensional finite element modeling using the Hill model and calibrated post-necking strain hardening curve was performed to obtain the force and strain history till the crack initiation. The crack propagation was numerically simulated employing a strain-to-failure model. The results from computations as global force-displacement relation, local strain distribution, and failure process are found in good agreement with experimental observations.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45879299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiphysics Numerical Simulation of the Transient Process in Electrochemical Machining","authors":"Y. Chen, Xiang Li, Jinyang Liu, Yichi Zhang","doi":"10.5755/j02.mech.31052","DOIUrl":"https://doi.org/10.5755/j02.mech.31052","url":null,"abstract":"To fully understand the electrochemical machining profile, a multi-physics coupling simulation model including flow-electric-temperature-structure field were established to analyze the corrosion process of the anode material and the change trend of temperature,hydrogen volume fraction, electrolyte conductivity and current density in the processing gap.The analysis results show that the temperature and hydrogen content gradually increase along the process direction.The current density and material removal showed a parabolic trend of the upper opening and the lower opening, respectively.The simulation of the different physical field changes in the electrochemical machining blade profile can not only better understand the complex physical phenomena in the machining, but also provide a theoretical basis for the selection of actual electrochemical machining parameters.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45041096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Soft Impacts in Elements of Pipe Robots","authors":"K. Ragulskis, B. Spruogis, M. Bogdevičius, A. Matuliauskas, V. Mištinas, L. Ragulskis","doi":"10.5755/j02.mech.29342","DOIUrl":"https://doi.org/10.5755/j02.mech.29342","url":null,"abstract":"Vibrators with deformable impact support under harmonic excitation are especially useful in the case when their stationary regimes of motion are stable. This is useful in practice by applying those vibrators to single direction manipulators and various robots of space type. \u0000For practical application it is necessary to reveal dynamical qualities of the system from where it would be possible to determine optimal regimes. For this purpose investigations of dynamics of the system by numerical methods were performed. \u0000Investigation of dynamics of impact interactions in elements of robots is an important engineering problem. Dynamics of soft impacts in elements of manipulators and robots is investigated. The model of the investigated system is described. Numerical investigations for various parameters of the system are performed. Free and forced vibrations are investigated. \u0000From the presented results it can be noted that for the smaller values of the coefficient of stiffness of the support period of steady state motion coincides with the period of the exciting force, while for the higher values of the coefficient of stiffness of the support period of steady state motion is equal to two periods of the exciting force. Thus it is concluded that with the increase of the coefficient of stiffness of the support behavior of the investigated vibro impact system with soft impacts experiences essential changes. \u0000Main characteristics of steady state motion as functions of frequency of excitation are investigated. From the presented results the minimum and maximum inter impact intervals as functions of frequency of excitation, minimum and maximum velocities before impact as functions of frequency of excitation, minimum and maximum minimum displacements in inter impact intervals as functions of frequency of excitation are seen. Three resonant zones of expected single valued motions are observed in the presented results. They correspond to optimal regions of operation of the vibro impact system with soft impacts. \u0000Results of the performed analysis of dynamic interactions with soft impacts in the elements of manipulators and robots are used in the process of design of pipe robots of advanced type.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46597551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and Numerical Study on LCF Crack Propagation of Coiled Tubing Steel","authors":"J. Zhong, Guanghui Zhao, Litong Wang, Yi He, Siou-Han Hu","doi":"10.5755/j02.mech.31056","DOIUrl":"https://doi.org/10.5755/j02.mech.31056","url":null,"abstract":"Coiled tubing (CT) is a joint-less long oil pipe that is wound around a reel and can be run and pulled continuously. Due to the particularity of the operating process, low-cycle fatigue (LCF) failure of the CT constitutes the main production cost. Aiming at the characteristics of small diameter and thin wall of CT, a single-edge-notched (SEN) arc specimen was designed and machined. LCF tests were conducted with force-controlled mode. Cyclic softening of the CT steel was presented and crack growing rates were measured. Meanwhile, finite element simulation was carried out to obtain the relationships among J-integral, crack size and load. Based on the experimental and numerical results, the speed of the LCF crack growth of the CT steel is expressed as an explicit function of the J-integral. It provides a basis for predicting the LCF life of the CT under working conditions from the perspective of crack propagation.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46836844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cemented Carbide Layer Thickness Optimization of Carbide Anvil Based on Thermodynamic Coupling","authors":"G. Xie, Tao Wang, Liangwen Wang, Xiaoyun Gong, Shixin Zhang, Zeheng Zhi, Ziye Zhao, Xiaojun Yang","doi":"10.5755/j02.mech.30808","DOIUrl":"https://doi.org/10.5755/j02.mech.30808","url":null,"abstract":"This paper presents cemented carbide layer thickness optimization of a carbide anvil based on thermodynamic coupling analysis. In our method, the established carbide anvil system through SolidWorks is firstly imported into the finite element software. The temperature field and thermal-mechanical coupling field of the carbide anvil system are analyzed. From the simulation results, it can be found that the contact stress of steel ring under temperature load is increased by 17.9% compared with that without temperature load. Thus, the service life of carbide anvil under temperature load is lower than that without temperature load. In addition, the four edges of anvil are prone to fatigue cracks due to the phenomenon of shear stress concentration. This is consistent with the actual crack location of cemented carbide anvil, which verifies the accuracy and rationality of thermal-mechanical coupling simulation. The thickness of cemented carbide layer is optimized based on thermodynamic coupling. The optimization results show that the thickness of 1.8cm is the best when size ranges from 1.8cm to 2.2cm. The maximum contact stress, the maximum shear stress, the temperature are all reduced by 387.5MPa, 110.55MPa, and 10.11℃, respectively.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45366567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved Particle Swarm Algorithm Based Multi-objective Optimization of Diaphragm Spring of the Clutch","authors":"Junchao Zhou, Yihan Liu, Jilong Yin, J. Gao, Naibin Hou","doi":"10.5755/j02.mech.27984","DOIUrl":"https://doi.org/10.5755/j02.mech.27984","url":null,"abstract":"Considering that diaphragm spring is the core component of the mechanical clutch, the optimization to which plays practical roles in engineering practices, the multi-objective optimization model for the diaphragm spring of the clutch is established in this article. Aiming at the difficulty in local extremum due to pre-maturity of inertia weight and treatment on nonlinear constraint condition of standard particle swarm optimization (PSO), the improved particle swarm algorithm（Improved PSO） based on dynamic weight and hierarchical penalty function in consideration of the degree of congestion is proposed in this article to improve the original particle swarm algorithm. According to the results of calculating examples, the improved particle swarm algorithm can achieve better global searching ability and convergence ability; when compared with the calculating results of the penalty function algorithm, the genetic algorithm and the NSGA-II algorithm, the pressing force of the diaphragm spring with the new algorithm is increased by 3.24%, and the steering separation force is decreased by 20.09%. The diaphragm spring has better pressing force stability and operating lightness, verifying the correctness of the model and the algorithm proposed in this article.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48754692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using the Stress Concentration Factor in Determining the Fracture Toughness","authors":"Goksel Saracoglu","doi":"10.5755/j02.mech.31226","DOIUrl":"https://doi.org/10.5755/j02.mech.31226","url":null,"abstract":"This paper offers the use of stress concentration factor in determining the critical fracture stress and fracture toughness of polymeric composite materials at various crack length ratios. The stress intensity factor has been turned into a function of the stress concentration factor derived from the maximum stress occurring at the notch tip and the tip stress generated by the force applied to the sample. This conversion allowed the use of a fixed theoretical radius (1.2732 mm) instead of the actual radius of the notch or crack. On the edge cracked three-point bending and tensile samples, the specified method detects the three point bending fracture stresses with a maximum error rate of 1.2%. This study also establishes a relationship between the clamped end and the pin-loaded tensile specimens and states that the underlying mechanism of the stress intensity factor of the clamped end tensile specimen is based on the normalization of the stress intensity factor of the pin-loaded conditions with the geometric correction factor.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44100281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}